Finally.

After three seasons of Jackie (Edie Falco, The Sopranos) successfully covering up her misdeeds time and again, Showtime's Nurse Jackie finally stops spinning its wheels and moves forward as season four begins (9 p.m. Sunday, followed by new episodes of The Big C and The Borgias).

The problem facing the writers of Nurse Jackie is the same one that faced the writers of United States of Tara or The Sopranos or The Shield: When you create a TV show around an anti-hero, you run the risk of repeating the same cat-and-mouse games lest you undercut the premise of the show. But without significant change, there's no forward momentum and a show stagnates.

Nurse Jackie has tried to thread the needle throughout its run, bringing best friend Dr. O'Hara (Eve Best) in on Jackie's drug habit and last season's dissolution of Jackie's marriage to Kevin (Dominic Fumusa).

As season four begins, more of Jackie's closely kept secrets come out. It's about time. In order to grow as a TV show, Jackie needed some growth as a person. She even goes to rehab for a few episodes, and viewers probably won't miss her at All Saints Hospital.

As much as Nurse Jackie is a star vehicle for Falco, the Jackie character always has been the least fun to spend time with. Scenes with O'Hara or adorably awkward nurse Zoey (Merritt Wever) or cringe-inducing Dr. Cooper (Peter Facinelli) or squishy-faced Dr. Akalitus (Anna Deavere Smith) delight in their humor; too often, scenes with Jackie, through no fault of Falco's, are laced with bad personal choices that blunt the humor generated by Jackie's work colleagues.

-- ROB OWEN

First Published April 7, 2012, 4:00 a.m.